The perimeter of a rectangle is 200 cm, its width is 50 cm. Find its area of this rectangle.

P = 200 cm.

b = 50 cm.

S =?.

1) We express the unknown side of the rectangle, from the formula for the sum of all its sides:

Р = 2а + 2b, therefore, to find the first term, we subtract the second from the sum:

2a = P – 2b = 200 – 2 * 50 = 200 – 100 = 100.

The second factor is equal to the product divided by the first:

b = 100: 2 = 50 cm – length.

2) The area of the rectangle is calculated by the formula:

S = a * b = 50 * 50 = 250 cm² or 2.5 dm². Since 1 dm² = 100 cm².